1. Technical Field
This invention relates in general to communications networks and, more particularly, to optimization of a network design.
2. Description of the Related Art
In the design and modification of a network architecture, such as a local exchange network or a core (backbone) network, both capital expenditures and operational expenditures should be considered in evaluating the total cost of the network. Capital expenditures would include the cost of new equipment and, if necessary, additional lines (such as optical fiber lines). Operational expenditures include those expenses necessary to operate the network at the service provider's expectations. In determining the operational expenditures, the availability of the network should be considered are part of the cost, through maintenance and repair efforts.
The solution that provides the lowest capital expenditures may often not result in the lowest total cost. This would be true if the network with the lowest capital expenditures does not meet the service provider's requirements for availability or if additional operational expenses would be required to bring the network's availability to a reasonable level in an attempt to shorten the Mean Time To Repair (MTTR) by spending more on repair crew efforts.
With the large number of options available for a network configuration, such as parameters related to traffic grooming, express routes, network dimensioning, and so on, it is virtually impossible to find a solution that is a near optimum solution. Integrating similar constraints relating to availability, would increase the complexity of the problem which is already non-trivial to cope with. Moreover, the objectives of availability and cost are often conflicting. This means that when one of the objectives (e.g. cost or availability) improves, the other one (availability or cost) worsens. Service providers generally are satisfied to find a solution that works, without considering other options. This can lead to excessive present costs due to capital expenditures or excessive future costs due to ongoing operational expenditures.
With communications being a highly cost competitive field, it has become more necessary to reduce total costs.
Therefore, a need has arisen for finding a near-optimal solution for designing a network.